"We present the new notion of Read-Eval-Synth Loop (RESL), which extends REPL by providing in-place synthesis on parts of the expression provided by the user. Our experiments show that RESL reduces programmers’ effort, increases their task completion rate, and improves program correctness." "The user does not know how to construct a range, so instead, they mark the current array expression as a portion of the program that should be replaced. This is called a sketch: the user expresses their intent to keep everything outside this sub-expression as is, while turning it into a hole to be replaced with a new expression." http://cseweb.ucsd.edu/~hpeleg/resl-oopsla20.pdf